PROJECT SUMMARY The long-term objective of this research program is to improve the care of patients harboring unruptured as well as ruptured intracranial aneurysms. Unruptured aneurysms are present in approximately 6 to 10 million Americans. An estimated 30,000 of those aneurysms will rupture annually resulting in about 40% fatality. The most modern techniques for aneurysm treatment include minimally invasive, nonsurgical approaches using platinum coils. While these coils decrease the potential negative impact on patients compared to open brain surgery, serious shortcomings remain with this endovascular approach. The most critical of these failures is due to insufficient packing of the aneurysm resulting in ?compaction? of the coil mass, in which the aneurysm re- opens over time and requires re-treatment. Another serious drawback of current coils is the inert nature of platinum, which fails to promote tissue growth. This significantly prolongs healing time and increases chances of complications such as inflammation or recurrence by allowing more time for compaction. To address these issues and improve aneurysm healing, we developed a device composed of a highly fibered polymer jacket containing a radiopaque coil. Initial animal trials have shown this device to accelerate healing due to several advantageous features. First of these is implementation of highly thrombogenic fibers to construct the textile outer surface that promotes connective tissue growth both inside the aneurysm and at the neck. Secondly, the soft outer jacket is compressible yet elastic, which allows for a higher packing density to counteract compaction. Thirdly, early animal study results show robust healing with little to no inflammation at one month. The research described in this application will demonstrate safety and efficacy of this new approach to permanently healing intracranial aneurysms. We will apply a well-described rabbit model of aneurysms to show that a highly-fibered device improves tissue growth, without increased risk of stroke, and that the healing within the aneurysms is improved as compared to ?gold standard? platinum coils. If successful, this translational research program will directly improve patient outcomes.